ATLANTA — The Supreme Court of Georgia ruled against a company accused of partnering with a Texas firm to send more than 300,000 junk faxes to metro Atlanta homes and businesses, meaning it could be liable for a $459 million penalty.

In an opinion released Monday, the court reversed a lower court decision, ruling against home maintenance firm American Home Services Inc.

Norcross-based A Fast Sign Co., which said its fax machine became tied up with unsolicited ads for the company, sued it in 2003 in what became a class-action lawsuit.

A trial court entered a judgment against American Home Services for $459 million -- or $1,500 in damages for each of the 306,000 junk faxes -- but an appeals court threw it out. In Monday's ruling, the supreme court sent the case back to the appeals court, saying the company could still remain liable for $459 million, depending on how legal matters in the case are resolved.

A key issue is how the Telephone Consumer Protection Act of 1991 is interpreted, and whether it's necessary to show that faxes sent were actually received.

The appellate court had ruled that the trial court incorrectly applied the federal act, prompting Fast Sign Co.'s appeal to the state supreme court.

In the ruling released Monday, the state supreme court concluded that the federal act "prohibits a person from using a device to send an unsolicited advertisement to a telephone facsimile machine."

The court's ruling states that "a sender is liable for the unsolicited advertisements it attempts to send to fax machines, whether or not the transmission is completed or received by the targeted recipient."